Purchasing Club Access Awards (or GoH) on eBay

Basic Discoverist here. We are headed to London after New Years, staying at HR Blackfriars. Will book two rooms on points (parent and kids). I have heard about people getting Club Access Awards off eBay. Not sure if that is a good idea. I have a couple questions:

• If you have done this, what are your thoughts? Successful? Worth it? Not worth the risk and the ToS violation?
• Since I am booking with points, the rooms will be on separate reservations. Do I need two CAAs? Would I be able to call, combine reservation, and then apply one?
• Am I able to apply a CAA after booking, or do I have to use it at time of booking?

Thanks!